U.S. Pub. No. 2007/0074114 to Adjali et al. discloses a human-computer interface for automatic persuasive dialog between the interface and a user and a method of operating such an interface. The method includes presenting a user with an avatar or animated image for conveying information to the user and receiving real time data relating to a personal attribute of the user, so as to modify the visual appearance and/or audio output of the avatar or animated image as a function of the received data relating to a personal attribute of the user.